INCIDENTS () SECURITYFOCUS COM

[Thor () HammerofGod com]

FWIW, IIS5.0/Exchange 2000 SMTP uses TCP 53 for DNS queries.
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> Jason Lewis wrote:
> > DNS queries are on UDP port 53.  TCP port 53 is used for zone transfers.
By
> > blocking TCP port 53 I can't do zone transfers, but clients can still do
> > lookups on UDP 53.  Since I have blocked TCP port 53, I have seen a
decrease
> > in attack attempts on my name servers, primarily because that port isn't
> > open.  I do still see scans for the DNS ports, but nothing more than a
port
> > scan.
> >
> > My question is...Can anyone come up with any pros/cons of doing this?